CW THz spectroscopy of polymers using plasmonic surface-wave sensors

Abstract

Lamellar metal gratings with sub-wavelength slits have been fabricated and characterized. They feature a transmission resonance which is highly sensitive to material layers attached to the grating surface. At first, gratings with resonant features at 85GHz are investigated. The transmission spectrum recorded with a commercial Vector Network Analyzer is in good agreement with the data obtained from a photoconductive continuous-wave THz system. Further, the grating dimensions are scaled down for an operation frequency of 430GHz. Sandwiched between polymer foils, the transmission resonance of the grating is shifted in frequency and the permittivity of the layers is extracted from the induced shift with an analytical model. The received results coincide with literature data very well.

Lamellar metal gratings with sub-wavelength slits have been fabricated and characterized. They feature a transmission resonance which is highly sensitive to material layers attached to the grating surface. At first, gratings with resonant features at 85GHz are investigated. The transmission spectrum recorded with a commercial Vector Network Analyzer is in good agreement with the data obtained from a photoconductive continuous-wave THz system. Further, the grating dimensions are scaled down for an operation frequency of 430GHz. Sandwiched between polymer foils, the transmission resonance of the grating is shifted in frequency and the permittivity of the layers is extracted from the induced shift with an analytical model. The received results coincide with literature data very well.